To paraphrase the old song: Catch a falling star and put it on your rooftop.

In this case, the star is that old favorite, the sun. On the heels of our report last week that prices of solar panels will plunge to $1.00 per watt by early 2012, Ernst & Young has spotted a similar free fall.

According to the Guardian newspaper in the UK, the consulting giant predicts that the installed price of solar panels will plunge to $1.00 per watt by 2013.

Last week’s report by IHS iSuppli said that the panels themselves will plummet to $1.00 per watt by early 2012, but that installed prices would at that time hover around $2.00 per watt. IHS iSuppli looked at panels made from crystalline silicon photovoltaics, the most common form of solar cell.

We all know about lies, damn lies and statistics, so take note that the two research and consulting firms are a tad apart on their hard numbers.

E&Y says the current installed price is $1.50, while IHS iSuppli would put it at well over $2.00.

But there’s a common thread – both companies show the price dropping off a cliff.

As E&Y notes, $1.50 is down from more than $2.00 in 2009. E&Y produced the report for the UK’s Solar Trade Association.

The Guardian points out that one factor driving down the price is the rapid decline in the raw material of silicon. “The report coincides with new data from Bloomberg New Energy Finance that show a drastic 28% month-on-month drop in the spot price of high-grade silicon, the raw material used in most PV panels,” the Guardian says.

Surely aggressive pricing by Chinese manufacturers also plays a part.

With prices dropping almost as fast as baseball’s Florida Marlins, is the moment coming when solar will achieve “grid parity” and make it competitive with, say, a coal-fired power plant?

E&Y says stay tuned. As fossil fuel prices rise, the time will come when, yes, it will make economic sense to generate your own rooftop electricity rather than plug into the grid.

The Guardian notes,“The report predicts that, with continued support in the short term, the levellised cost of large-scale solar will be no higher than retail energy prices by 2016-19. This suggests that within 10 years companies with large electricity demands will find it cheaper to install unsubsidized solar than to buy energy via the grid in the traditional way.”

If only solar electricity storage technology would advance at the same pace. Then, as the song would say, you could even save it for a rainy day.